With over 1 million sufferers today, aphasia is an impairment common after left-hemisphere stroke that affects the production or comprehension of spoken, written, or gestured speech. This proposal seeks to provide foundational research to support development of a treatment theory based on powerful learning principles derived from basic psychological research. The contribution of this theory will be to maximize the efficacy and long-term impact of existing treatments targeting spoken language impairments in aphasia. The proposed research will evaluate with controlled experimentation the application of the following core learning principles in aphasia: (1) retrieving target information from long-term memory (i.e., retrieval practice) powerfully bolsters future success in retrieving the same information; (2) retrieval practice effects increase with increasing retrieval effort up to the point of desirable difficulty, where retrieval is maximally difficult, yet successful; (3) spacing retrieval practiceover time promotes long-term retention. The proposed studies seek to delineate the role of these principles in the amelioration of word-retrieval impairments in aphasia. In Study 1, retrieval practice training will involve the presentation of a picture to be named with cueing support (i.e., first letter/sound). The effects of retrieval practice training on later naming performance will be measured against a baseline condition that does not involve retrieval from long-term memory (i.e., repetition training, where the word is seen/heard and repeated). Study 2 will manipulate the time elapsed (i.e., training lag) between an initial repetition opportunity and retrieval practice. Based on prior work, training lag is expected to be associated with decreasing retrieval success during training (reflecting increasing retrieval difficulty). However, supporting a role for retrieal effort on subsequent naming, increases in training lag should be associated with increasing performance at final naming assessment. Study 3 will incorporate the most optimal lag from Study 2 into a distributed schedule of learning where retrieval is practiced for individual items multiple times. This optimized distributed schedule will be compared to a non-distributed schedule in order to establish the relevance of spaced retrieval practice in the naming performance of speakers with aphasia. The proposed research will serve as pilot studies for an R01 dedicated to the development of efficacious treatments of expressive language impairment in aphasia, guided by a theory of treatment based on the principles investigated here. PUBLIC HEALTH RELEVANCE: The focus of this grant is chronic aphasia, an impairment common after left-hemisphere stroke in the ability to comprehend or produce language. This research proposal seeks to establish the relevance of powerful learning principles derived from basic psychological research in aphasia. Determining whether such principles operate in aphasia will support development of a theory of treatment that will ultimately help maximize the beneficial impact of common treatment methods of aphasia. )